Traditional pet litters for cats and other small animals are granular and clump when moistened. Conventional litter scoops are consequently designed with holes or slits to allow clumps and solid waste to stay above the holes or slits to facilitate their disposal. Loose grains of unused litter fall through the holes or slits back into the litter tray.
Alternatively, non-clumping pelleted or tableted litter can be used for cats and other small animals. In general, the pelleted non-clumping litter will absorb moisture, which generally causes the pellet or tablet to expand and become friable, loose wet grains of powder. These grains of loose powdery material cannot be scooped out of the litter box or tray with traditional cat litter scoops, since the holes or slits of conventional scoops allow clumps and solid waste (i.e., used litter) to stay above the holes or slits, and allow loose grains of litter to fall through the holes or slits back into the litter tray.
With pelleted litter, where the pellets expand and become friable or become grains of powder, a scoop system is needed for removing the wet friable powder, while at the same time enabling the return of unused dry pellets to the litter tray.